Tower crane attachment



June 5, 1962 K. F. POTTER ETAL 3,037,641

TOWER CRANE ATTACHMENT Filed Feb. 27, 1961 3 Sheets-Sheet 1 F112: 1 IL/YQ 67 70 W )4 rromvsrs June 5, 1962 K. F. POTTER arm.

TOWER CRANE ATTACHMENT 5 Sheets-Sheet 3 Filed Feb. 27, 1961 m w mmw w m; M mn $2 2 MM k6 fi 3,037,641 TOWER CRANE ATTACHMENT Kenneth F. Potter, St. Paul, and Archer W. Brown, Minneapolis, Minn, assignors to American Hoist & Derrick Company, St. Paul, Minn.

Filed Feb. 27, 1961, Ser. No. 91,692 Claims. (Cl. 212--46) The present invention has relation to an attachment for a tower crane and more particularly to a boom and jib assembly that is easily installed and set up to reach the tops of high buildings.

When installing an elongated boom and a jib used for reaching the tops of high buildings a considerable amount of labor and time is expended in assembling the boom and jib and it involves a considerable amount of high level work.

The present invention, in the form as disclosed, illustrates a boom and jib assembly that may be easily attached to a crane base and may be raised into working position with all the lines, including the load line, fully reeved so that the machine is ready to go immediately when it is raised into position. When the attachment is to be erected, the boom is pinned in a horizontal position to the crane base with the jib folded underneath the boom tip and secured to the boom. The boom hoist line and the jib actuating line are fully reeved, as is the load line that extends from the jib. The mechanical advantage of the boom hoist line and the jib actuating line is such that the crane base itself has sufficient power to raise the entire boom vertically into working position. A rigid back brace is then pinned to the top of the machine frame.

The raising of the boom is done with a ten part hoist line. The first four parts of the line leading from the hoist drum are connected to the jib backstay lines and the last six parts of the line lead to pendants from an outer section of the boom. When the boom is hoisted, the jib is secured with respect to the boom so that all ten parts of the line are active to raise the boom to working position. When the boom is in place and the back brace has been secured to the base the hoist cable is locked with respect to the sheave between the fourth and fifth parts of the line in the rigging so only the first four parts of the line are operative. The boom is then locked in working position and the angle of the jib may be controlled through the instrumentality of the hoist drum. In this manner the hoist drum doubles as a jib actuating drum and also as a drum that is used to hoist the entire boom and jib assembly into place. The basic machine may convert into a standard lift crane by removing the long boom and installing conventional rigging.

It is an object of the present invention to disclose an easily installed tower crane attachment that can be raised into position fully reeved and is immediately ready for use once it is positioned.

In the drawings,

FIG. 1 is a side elevational view of a tower crane attachment made according to the present invention shown in position adjacent a building;

FIG. 2 is a side elevational view of the device of FIG. 1 with the boom shown in a horizontal position before being elevated to working position;

FIG. 3 is a schematic representation of the hoist line reeving used in connection with the operation of the tower crane attachment;

FIG. 4 is a fragmentary side elevational view of a jib and the upper end of the tower crane boom;

FIG. 5 is a fragmentary end elevational view of hoist line idler sheaves for the tower crane attachment with parts in section and parts broken away to show a method of clamping the cable in relation to one of the sheaves and taken as on line 5--5 in FIG. 1;

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FIG. 6 is a sectional view taken as on line 66 in FIG. 5, and

FIG. 7 is a schematic representation of a control circuit for a hoist drum.

Referring to the drawings and the numerals of reference thereon, a tower crane boom 15 is pivotally attached to a base 16 of a crawler crane body 17 as at 18. The boom is a five-section boom and is sufiicient in length to reach the top of a tall building 19. A jib 20 is pivotally attached to a pair of plates 22, 22, as at 21. These plates are fixedly attached to the sides of the boom 15 adjacent an outer end thereof. A rigid back brace 23 is fixedly attached to the boom and is pinned to the crawler crane body 17, as at 24, when the boom is in the elevated position. A hoist drum 25 is mounted on the crawler crane body and is powered with a suitable source of power (not shown). The hoist drum 25 has a hoist cable 26 that is controlled by the drum and passes over a first guide sheave 27 and a second guide sheave 28. The cable 26 is reeved in a four part line to a pair of jib control sheaves 29, 29 that are mounted on a shaft 30 to be rotatable with respect to a pair of jib backstays 31, 31. The hoist cable is reeved around a group of idler sheave-s indicated at 35 that are mounted on an A frame 36 extending up from the crawler crane body 17. The cable is also reeved in a six part line to three boom hoist sheaves 37 that are mounted on a boom hoist shaft 38 to be rotatable with respect to a pair of boom pendants 39, 39. The cable 26 is dead ended, as at 40, with respect to the A frame 36.

The first four parts of the line leading from the hoist drum are directly connected to the jib through the jib backstays 31 and associated sheaves 29. The other six parts of the ten part hoist line are associated with the boom through the boom pendants 39, 39 and their associated sheaves 37. i

A transition sheave 41 is located in the group of idler sheaves and is the sheave that receives the cable from the last jib sheave and directs the cable toward the first boom sheave. The transition sheave 41 is provided with a clamping device 42. The clamping device 42 consists of two clamping blocks 45, 45 that are slidably mounted on a base 46 and are movable toward and away from each other through the instrumentality of a compound screw 47. The screw 47 has a first section 48 and a second section 49 that have threads of opposite hand so that upon turning the screw in one direction the blocks will be moved toward each other and, when the screw is turned in the other direction, away from each other as desired. The screw is rotatably mounted and guided in suitable fashion so that the blocks 45, 45 may be forced together to engage the cable 26 and clamp it tightly against the sheave 41.

The jib backstays 31, 31 extend from the jib sheaves 29 upwardly to engage a jib mast 56 that is pivotally mounted as at 51 to the jib support plates 22, 22. A saddle 54 is fixedly attached to a strut or leg 55 that in turn is fixedly attached with respect to jib mast 50.

A jib backstop 56 is fixedly attached with respect to the jib 20 and has a brace 57 extending between the backstop and the jib. A jib backstop spring 58 is mounted on a plate 59 with a bolt 60 and serves to help overcome the weight of the jibsuspension tackle so the jib will pivot forwardly after it has been raised to a near vertical position. A limit switch 61 is mounted on plate 59 and an ear 62 is fixedly attached to a jib backstop 56 in position to engage the limit switch and disable the controls for the hoist drum when the jib has been raised to a predetermined maximum position. This prevents the jib from being pulled rearwardly over center. A jib pendant 67 extends from the jib mast 50 to the outward end of the jib and has a turn buckle 68 for adjusting the angular relationship between the mast and the jib.

The iib mast 50 is pivoted independently of said jib.

O In this manner, when the jib is in its folded or tip down position, the mast extends forwardly beyond the pivot point 21 of the jib and provides a leverage for swinging the jib from its folded position. In all angular positions of the jib the mast keeps the jib pendants away from the jib pivot 21 so there is a moment about the pivot effective to raise the jib.

In FIG. 7, a schematic representation of the apparatus used for controlling the hoist drum 25 is shown. A control lever 80 that is mounted to base 16 in the crane cab is connected through suitable linkage to a control valve 81 that controls air under pressure from an air pressure source 32. A clutch 83 is operably associated with the hoist drum and is engaged when subjected to air pressure. A brake 84 is also operably associated with the hoist drum and is released when subjected to air pressure. The valve 81 directs air pressure to the clutch or brake through suitable lines 87, 87. A double check valve 85 is located between the air lines and serves to direct air to the clutch and brake simultaneously when the clutch line is pressurized and to ,the brake only when the brake line is pressurized. A normally energized solenoid operated valve 86 is connected to a source of electromotive force 88 and is located in the clutch air line 87 and is controlled by limit switch 61. When the jib is raised to its limit, ear 62 opens the limit switch 61, the solenoid valve 86 is de-energized and the hoist drum is disabled as the air pressure to the clutch is cut off. This prevents the jib from being hoisted too far and being damaged.

A load line 69 is reeved along the boom and the jib on suitable sheaves 70 and is controlled with a load hoist drum 71 that is mounted on the crawler crane body 17 and is operated with suitable controls (not shown). The outer end of the load line 69 may be lowered to the ground, using a suitable counterweight, and it may then be used to raise a concrete bucket 72 or some other object that is to be placed on top of the building 19.

A hand winch 73 that has a locking device is used with a line 74 that is attached to load line 69 to hold the jib in its folded position, indicated at 75 in FIG. 2 and in dotted lines in FIG. 1, when the boom is being raised into working position.

Operation When the tower crane attachment is to be used, the boom is placed in horizontal position with the jib folded underneath as illustrated in FIG. 2. The entire boom assembly, including the rigid back brace 23, is pivotally mounted to the crawler crane body 17 as at 18. The line 74 from the hand winch 73 is attached to the load line 69, as at 76 in FIG. 2, and the hand winch is then locked to keep the jib in this folded position. The hoist line 26 is then reeved through its pulleys as described before, with four parts of the ten part line going directly to the jib sheaves 29 and the other six parts of the line going to the boom hoist sheaves 37. The clamping device 42 is loosened to allow the transition sheave 41 to rotate. Thus the entire line is operating. It will be noted in FIG. 2 that the strut 55 and the saddle 54 are used to hold the jib backstay lines 31 away from the other mechanism when the jib is in its folded position and also increase the lifting leverage with the boom in its horizontal position and the jib in its folded position.

When the boom has been attached to the crawler crane body 17, the jib secured in its folded position, and the jib and boom assembly fully reeved, the hoist drum is actuated and the boom is raised into its upright position as illustrated in FIG. 1. The hoist mechanism has sufficient power to raise the boom and jib assembly by itself, as the ten part line gives a ten to one mechanical advantage. The jib backstay lines 31 and the boom pendants 39 act together to raise the jib and the tower crane boom as a unit. When the tower crane boom is in its upright position the rigid backstop 23 is pinned to the top of the crawler crane body, as at 24, with suitable fastening means and the clamping blocks 45, 45

are moved to position to clamp cable 26 against the transition sheave 41. This in effect dead ends the cable 26 at the transition sheave 41 and effectively eliminates from the reeving the six parts of the line going to the boom pendants.

The two section reeving is used to provide sufficient mechanical advantage so the hoist drum can raise the boom from its horizontal position and still provide control means for the jib that is fast enough to be usable when the boom is in working position. The four part line to the jib permits rapid operation.

The hoist drum then is active to control only the four part line that goes to the jib backstays. The hand winch is released and the load line 69 and the hand winch line 74 are lowered to the ground and disconnected. The dotted position of the jib in FIG. 1 shows the jib in posi tion after the hand winch has been released and before the lines have been lowered. The jib may then be raised into its Working position by activating the hoist drum which acts through the first four part reeving of cable 26 to lift the jib. The load hoist drum 71 may then be used to raise or lower the load line and conse quently raise or lower any load that is to be placed on the building 19.

Through the use of a foot boom and a 60 foot jib on a crane base of suitable size the unit can be used to reach above a 135 foot high building and place concrete or other material 55 feet back from the face of the building using a one yard concrete bucket. The entire boom is positioned ready to use without sending men higher than the top of the crawler crane body 17.

The hoist drum may be used to change the angle of the jib with respect to the boom 15' and the backstop spring and limit switch limit the travel of the jib 20 to position as shown in dotted lines in FIG. 1, and indicated at 79. This prevents the jib from going over center and resulting in damage to the boom and the jib mechanism.

When the boom is to be lowered, the jib will again be placed in its folded position and the load line 69 secured with the hand winch line and hand winch. The clamping device 42 on the transition sheave 41 will be loosened to allow the transition sheave to rotate and the full ten part reeving of the cable 26 will be effective. The back brace 23 may then be loosened from the crawler crane body and the boom hay be lowered to the ground and disconnected.

The crawler crane body will convert to any standard lift crane, drag line or clamshell by putting on another conventional boom and associated equipment.

What is claimed is:

1. An attachment for.a crane having a hoist drum on a base, said attachment including an elongated boom mounted for movement about a substantially horizontal pivot on said base, a jib pivotally mounted adjacent an outer end of said boom, a jib mast pivotally attached with respect to an outer end of said boom, a jib pendant fixedly attached to said jib and operably associated with said mast, a plurality of jib sheaves operably associated with said jib mast, a plurality of boom sheaves operably associated with said boom, a plurality of idler sheaves rotatably mounted with respect to said base, a transition idler sheave rotatably mounted with respect to said base, a cable having a first end portion wound on said hoist drum and a secondend portion dead-ended with respect to said base, said cable being reeved from said drum first on said jib sheaves, on said idler sheaves and said boom sheaves, said transition idler sheave being positioned to receive said cable from a last jib sheave in the reeving and direct it toward a first boom sheave, means selectively locking said cable with respect to said transition idler sheave, and releasable means for preventing angular movement of said jib with respect to said boom.

2. An attachment for a crane having a selectively power operated hoist drum on a base, said attachment including an elongated boom mounted for movement about a substantially horizontal pivot on a base, a jib pivotally mounted adjacent an outer end of said boom, a jib mast pivotally mounted adjacent an outer end of said boom, a jib pendant attached between said jib and said mast, a boom pendant secured to an outer end portion of said boom, a plurality of boom control sheaves rotatably mounted with respect to said boom pendant, a jib backstay secured with respect to said jib mast, a plurality of jib control sheaves rotatably mounted with respect to said backstay, a plurality of jib idler sheaves rotatably mounted with respect to said base, a plurality of boom idler sheaves rotatably mounted with respect to said base, a transition idler sheave rotatably mounted with respect to said base, a cable having a first end portion wound on said drum and a second end portion dead-ended with respect to said base, said cable being reeved first on said jib sheaves, on said jib idler sheaves, on said transition sheave, on said boom sheaves and on boom idler sheaves, said transition sheave being positioned to receive the cable from a last jib sheave and direct it toward a first boom sheave in the reeving, means for selectively locking said cable with respect to said transition idler sheave, releasable means for preventing angular movement of said jib with respect to said boom, and a strut fixedly attached with respect to said jib mast and positioned to engage said jib backstay and hold said backstay away from said boom with said jib in said folded position.

3. The combination as specified in claim 2 wherein said jib mast holds said jib backstay away from said jib with said jib in said folded position.

4. The combination as specified in claim 3 wherein said idler sheaves are situated in a plane above the horizontal pivot and wherein said strut holds the jib backstay above said boom with the jib in said folded position.

5. The combination as specified in claim 4 wherein said means for locking said cable with respect to said transition sheave includes a pair of clamping blocks slidably mounted with respect to said transition sheave, and a screw threadably mounted with respect to said blocks, said screw being of configuration so that when it is turned in a first direction said blocks move toward each other to clamp said cable against said sheave and when it is turned in a second direction said blocks release said cable and sheave.

References Cited in the file of this patent UNITED STATES PATENTS 2,924,341 Bahr et al. Feb. 9, 1960 FOREIGN PATENTS 810,893 Germany Aug. 13, 1951 Wl5l73 Germany Sept. 6, 1956 

